Concentration-controlled Zn(II) coordination polymers constructed from mixed ligands for Fe3+ sensing

The reactions of 1,2-bis(4-pyridyl)ethylene (bpe) and 2,5-furandicarboxylic acid (H 2 fdc) with Zinc(II) salts in different concentrations resulted in two new complexes, [Zn(fdc)(bpe)]∙DMF ( 1) and [Zn 4 (fdc) 4 (bpe) 4 (H 2 O) 2 ] ∙DMF·2H 2 O ( 2) . At lower concentrations, 1 was formed, in which {Zn 2 (CO 2 ) 2 } can be seen as a 6-connected node, and the whole framework is a 2-fold interpenetrated pcu network. On the contrary, at higher concentrations, 2 was synthesized, in which all Zn 2+ ions act as 4-connected nodes, and the whole framework is a 5-fold interpenetrated dia network. 1 and 2 are proven to be promising sensors towards Fe 3+ ions with high sensitivity and selectivity through fluorescence quenching.